gnu: libarchive: Apply fixes including for CVE-2013-0211.

* gnu/packages/patches/libarchive-CVE-2013-0211.patch,
  gnu/packages/patches/libarchive-fix-lzo-test-case.patch,
  gnu/packages/patches/libarchive-mtree-filename-length-fix.patch: New files.
* gnu-system.am (dist_patch_DATA): Add them.
* gnu/packages/backup.scm (libarchive)[source]: Add patches.